Cardioprotective phosphonates and malonates

ABSTRACT

Pharmaceutical compositions including an effective amount of the compound of formula IV                    
     in which 
     R 1  is hydrogen or alkyl; 
     R 2  is —CHO, —CH 2 OH, —CH 3  or —CO 2 R 5  in which R 5  is hydrogen, alkyl, or aryl; or 
     R 2  is —CH 2 O-alkyl- in which alkyl is covalently bonded to the oxygen at the  3 -position instead of R 1 ; 
     R 3  and R 3 ′ are independently hydrogen or halo; or 
     R 3  and R 3 ′ taken together constitute a second covalent bond between the carbons to which they are substituent; and 
     R 4  is hydrogen; 
     or a pharmaceutically acceptable acid addition salt thereof, are taught. Also taught are methods of using the compositions, including for the treatment of myocardial infarctions, ischemia, congestive heart failure, arrhythmia, blood clots, hypertrophy, diabetes, insulin resistance, diabetes related damage, and obesity.

PRIORITY OF INVENTION

This application is a divisional of application Ser. No. 09/795,689, filed Feb. 28, 2001, now U.S. Pat. No. 6,605,612, which claims benefit from provisional application Serial No. 60/185,899, filed Feb. 29, 2000, which applications are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to pyridoxine phosphonate analogues, to pyridoxine malonate analogues, to their preparation, to pharmaceutical compositions thereof, and to treatments for cardiovascular and related diseases, for example, hypertrophy, hypertension, congestive heart failure, myocardial ischemia, arrhythmia, heart failure subsequent to myocardial infarction, myocardial infarction, ischemia reperfusion injury, and diseases that arise from thrombotic and prothrombotic states in which the coagulation cascade is activated; and treatments for diabetes mellitus and related diseases, for example, hyperinsulinemia, diabetes-induced hypertension, obesity, insulin resistance, and damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin connective tissue, or immune system.

BACKGROUND

Pyridoxal-5′-phosphate (PLP), an end product of vitamin B₆ metabolism, plays a vital role in mammalian health. In previous patents (U.S. Pat. Nos. 6,051,587 and 6,043,259, herein incorporated by reference) the role of pyridoxal-5′-phosphate, and its precursors pyridoxal and pyridoxine (vitamin B₆), in mediating cardiovascular health and in treating cardiovascular related diseases is disclosed.

The major degradation pathway for pyridoxal-5′-phosphate in vivo is the conversion to pyridoxal, catalysed by alkaline phosphatase. Thus, there is a need to identify and administer drugs that are functionally similar to pyridoxal-5′-phosphate such as pyridoxine phosphonate analogues or pyridoxine malonate analogues, that elicit similar or enhanced cardiovascular benefits, and that beneficially affect PLP-related conditions, but are stable to degradation by phosphatase.

SUMMARY OF THE INVENTION

The present invention provides for pyridoxine phosphonate analogues and to pyridoxine malonates. In one aspect, the present invention includes a compound of formula I:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃, —CO₂R₆ in which R₆ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ is hydrogen and R₄ is hydroxy, halo, alkoxy, alkylcarbonyloxy, alkylamino or arylamino; or

R₃ and R₄ are halo; and

R₅ is hydrogen, alkyl, aryl, aralkyl, or —CO₂R₇ in which R₇ is hydrogen, alkyl, aryl, or aralkyl;

or a pharmaceutically acceptable acid addition salt thereof.

In another aspect, the present invention includes a compound of formula II:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₅ in which R₅ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ is hydrogen, alkyl, aryl, or aralkyl;

R₄ is hydrogen, alkyl, aryl, aralkyl, or —CO₂R₆ in which R₆ is hydrogen, alkyl, aryl, or aralkyl; and

n is 1 to 6;

or a pharmaceutically acceptable acid addition salt thereof.

In another aspect, the present invention includes a compound of formula III:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₈ in which R₈ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ is hydrogen and R₄ is hydroxy, halo, alkoxy or alkylcarbonyloxy; or

R₃ and R₄ can be taken together to form ═O;

R₅ and R₆ are hydrogen; or

R₅ and R₆ are halo; and

R₇ is hydrogen, alkyl, aryl, aralkyl, or —CO₂R₈ in which R₈ is hydrogen, alkyl, aryl, or aralkyl;

or a pharmaceutically acceptable acid addition salt thereof.

In another aspect, the present invention includes a compound of formula IV:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₅ in which R₅ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ and R₃′ are independently hydrogen or halo; or

R₃ and R₃′ taken together constitute a second covalent bond between the carbons to which they are substituent; and

R₄ is hydrogen or alkyl;

or a pharmaceutically acceptable acid addition salt thereof.

In another aspect, the invention is directed to pharmaceutical compositions that include a pharmaceutically acceptable carrier and a therapeutically effective amount of at least one compound of formula I, II, III or IV.

In another aspect, the invention is directed to a method of treating cardiovascular and related diseases, for example, hypertension, hypertrophy, arrhythmia, congestive heart failure, myocardial ischemia, heart failure subsequent to myocardial infarction, myocardial infarction, ischemia reperfusion injury, and diseases that arise from thrombotic and prothrombotic states in which the coagulation cascade is activated by administering a therapeutically effective amount of at least one compound of formula I, II, III or IV in a unit dosage form. For such a method, a compound of formula I, II, III or IV can be administered alone or concurrently with a known therapeutic cardiovascular agent, for example, angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, a vasodilator, a diuretic, an α-adrenergic receptor antagonist, a β-adrenergic receptor antagonist, an antioxidant, or a mixture thereof.

In still another aspect, the invention is directed to a method of treating diabetes mellitus and related diseases, for example, hyperinsulinemia, insulin resistance, obesity, diabetes-induced hypertension, and damage to eyes, kidneys, blood vessels, nerves, autonomic nervous system, skin, connective tissue, or immune system, by administering a therapeutically effective amount of a compound of formula I, II, III or IV in a unit dosage form. For such a method, a compound of formula I, II, III or IV can be administered alone or concurrently with known medicaments suitable for treating diabetes mellitus and related diseases, for example, insulin, hypoglycemic drugs, or a mixture thereof.

DESCRIPTION OF THE INVENTION

The present invention provides for pyridoxine phosphonate analogues such as, for example, ((2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)alkylphosphonates, and (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)azaalkylphosphonates) and to pyridoxine malonate analogues, such as, for example, ((2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethyl)malonates), pharmaceutical compositions, and methods for treatment of cardiovascular and related diseases, and diabetes mellitus and related diseases.

It is to be understood that the recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

It is to be understood that all numbers and fractions thereof are presumed to be modified by the term “about.”

It is to be understood that “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds.

It is to be understood that some of the compounds described herein contain one or more asymmetric centers and may thus give rise to enantiomers, diasteriomers, and other stereoisomeric forms which may be defined in terms of absolute stereochemistry as (R)- or (S)-. The present invention is meant to imclude all such possible diasteriomers and enantiomers as well as their racemic and optically pure forms. Optically active (R)- and (S)-isomers may be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques. When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and unless specified otherwise, it is intended that the compounds include both E and A geometric isomers. Likewise all tautomeric forms are intended to be included.

The general definitions used herein have the following meanings within the scope of the present invention.

As used herein the term “alkyl” includes a straight or branched saturated aliphatic hydrocarbon redicals, such as, for example, methyl, ethyl, propyl, isopropyl (1-methylethyl),

butyl, tert-butyl (1,1-dimethylethyl), and the like.

As used herein the term “alkoxy” refers to —O-alkyl with alkyl as defined above. Alkoxy groups include those with 1 to 4 carbon atoms in a straight or branched chain, such as, for example, methoxy, ethoxy, propoxy, isopropoxy (1-methylethoxy), butoxy, tert-butoxy (1,1-dimethylethoxy), and the like.

As used herein the term “aryl” refers to unsaturated aromatic carbocyclic radicals having a single ring, such as phenyl, or multiple condensed rings, such as naphthyl or anthryl. The term “aryl” also includes substituted aryl comprising aryl substituted on a ring by, for example, C₁₋₄ alkyl, C₁₋₄ alkoxy, amino, hydroxy, phenyl, nitro, halo, carboxyalkyl or alkanoyloxy. Aryl groups include, for example, phenyl, naphthyl, anthryl, biphenyl, methoxyphenyl, halophenyl, and the like.

As used herein the term “alkylamino” refers to —N-alkyl with alkyl as defined above. Alkylamino groups include those with 1-6 carbons in a straight or branched chain, such as, for example, methylamino, ethylamino, propylamino, and the like.

As used herein the term “arylamino” refers to —N-aryl with aryl as defined above. Arylamino includes —NH-phenyl, —NH-biphenyl, —NH-4-methoxyphenyl, and the like.

As used herein the term “aralkyl” refers to an aryl radical defined as above substituted with an alkyl radical as defined above (e.g. aryl-alkyl-). Aralkyl groups include, for example, phenethyl, benzyl, and naphthylmethyl.

As used herein the term “halo” includes bromo, chloro, and fluoro. Preferably halo is fluoro.

As used herein the term “alkylcarbonyloxy” includes alkyl as defined above bonded to carbonyl bonded to oxygen, such as, for example, acetate, propionate and t-butylcarbonyloxy.

Cardiovascular and related diseases include, for example, hypertension, hypertrophy, congestive heart failure, heart failure subsequent to myocardial infarction, arrhythmia, myocardial ischemia, myocardial infarction, ischemia reperfusion injury, and diseases that arise from thrombotic and prothrombotic states in which the coagulation cascade is activated.

Heart failure is a pathophysiological condition in which the heart is unable to pump blood at a rate commensurate with the requirement of the metabolizing tissues or can do so only from an elevated filling pressure (increased load). Thus, the heart has a diminished ability to keep up with its workload. Over time, this condition leads to excess fluid accumulation, such as peripheral edema, and is referred to as congestive heart failure.

When an excessive pressure or volume load is imposed on a ventricle, myocardial hypertrophy (i.e., enlargement of the heart muscle) develops as a compensatory mechanism. Hypertrophy permits the ventricle to sustain an increased load because the heart muscle can contract with greater force. However, a ventricle subjected to an abnormally elevated load for a prolonged period eventually fails to sustain an increased load despite the presence of ventricular hypertrophy, and pump failure can ultimately occur.

Heart failure can arise from any disease that affects the heart and interferes with circulation. For example, a disease that increases the heart muscle's workload, such as hypertension, will eventually weaken the force of the heart's contraction. Hypertension is a condition in which there is an increase in resistance to blood flow through the vascular system. This resistance leads to increases in systolic and/or diastolic blood pressures. Hypertension places increased tension on the left ventricular myocardium, causing it to stiffen and hypertrophy, and accelerates the development of atherosclerosis in the coronary arteries. The combination of increased demand and lessened supply increases the likelihood of myocardial ischemia leading to myocardial infarction, sudden death, arrhythmias, and congestive heart failure.

Ischemia is a condition in which an organ or a part of the body fails to receive a sufficient blood supply. When an organ is deprived of a blood supply, it is said to be hypoxic. An organ will become hypoxic even when the blood supply temporarily ceases, such as during a surgical procedure or during temporary artery blockage. Ischemia initially leads to a decrease in or loss of contractile activity. When the organ affected is the heart, this condition is known as myocardial ischemia, and myocardial ischemia initially leads to abnormal electrical activity. This can generate an arrhythmia. When myocardial ischemia is of sufficient severity and duration, cell injury can progress to cell death—i.e., myocardial infarction—and subsequently to heart failure, hypertrophy, or congestive heart failure.

When blood flow resumes to an organ after temporary cessation, this is known as ischemic reperfusion of the organ. For example, reperfusion of an ischemic myocardium can counter the effects of coronary occlusion, a condition that leads to myocardial ischemia. Ischemic reperfusion to the myocardium can lead to reperfusion arrhythmia or reperfusion injury. The severity of reperfusion injury is affected by numerous factors, such as, for example, duration of ischemia, severity of ischemia, and speed of reperfusion. Conditions observed with ischemia reperfusion injury include neutrophil infiltration, necrosis, and apoptosis.

Drug therapies, using known active ingredients such as vasodilators, angiotensin II receptor antagonists, angiotensin converting enzyme inhibitors, diuretics, antithrombolytic agents, α or β-adrenergic receptor antagonists, α-adrenergic receptor antagonists, calcium channel blockers, and the like, are available for treating cardiovascular and related diseases.

Diabetes mellitus and related diseases include hyperinsulinemia, insulin resistance, obesity, diabetes-induced hypertension, and damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin, connective tissue, and immune system. Diabetes mellitus is a condition in which blood glucose levels are abnormally high because the body is unable to produce enough insulin to maintain normal blood glucose levels or is unable to adequately respond to the insulin produced. Insulin-dependent diabetes mellitus (often referred to as type I diabetes) arises when the body produces little or no insulin. About 10% of all diabetics have type I diabetes. Noninsulin-dependent diabetes mellitus (often referred to as type II diabetes) arises when the body cannot adequately respond to the insulin that is produced in response to blood glucose levels.

Available treatments include weight control, exercise, diet, and drug therapy. Drug therapy for type I diabetes mellitus requires the administration of insulin; however, drug therapy for type II diabetes mellitus usually involves the administration of insulin and/or oral hypoglycemic drugs to lower blood glucose levels. If the oral hypoglycemic drugs fail to control blood sugar, then insulin, either alone or concurrently with the hypoglycemic drugs, will usually be administered.

The invention is generally directed to pyridoxine phosphonate analogues such as, for example, ((2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)alkylphosphonates, (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)azaalkylphosphonates) and to pyridoxine malonate analogues such as, for example, ((2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethyl)malonates), compositions including these analogues, and methods of administering pharmaceutical compositions containing a therapeutically effective amount of at least one of these analogues to treat cardiovascular and related diseases or diabetes and related diseases.

To enhance absorption from the digestive tract and across biological membranes, polar groups on a drug molecule can be blocked with lipophilic functions that will be enzymatically cleaved off from the drug after absorption into the circulatory system. Lipophilic moieties can also improve site-specificity and biovailability of the drug. The speed at which the blocking groups are removed can be used to control the rate at which the drug is released. The blocking of polar groups on the drug can also slow first-pass metabolism and excretion. An ester is a common blocking group that is readily hydrolyzed from the drug by endogenous esterases. Bundgaard, Design and Application of Prodrugs in A Textbook of Drug Design and Development (Krogsgaard-Larson & Bundgaard, eds., Hardwood Academic Publishers, Reading, United Kingdom 1991).

In one embodiment, the compounds of the present invention are analogues of pyridoxal phosphonate. The compounds of the invention include, for example, (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)methylphosphonate analogues. Such compounds are represented by the formula I:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃, —CO₂R₆ in which R₆ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ is hydrogen and R₄ is hydroxy, halo, alkoxy, alkylcarbonyloxy, alkylamino or arylamino; or

R₃ and R₄ are halo; and

R₅ is hydrogen, alkyl, aryl, aralkyl, or —CO₂R₇ in which R₇ is hydrogen, alkyl, aryl, or aralkyl;

or a pharmaceutically acceptable acid addition salt thereof.

Examples of compounds of formula I include those where R₁ is hydrogen, or those where R₂ is —CH₂OH, or —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁, or those where R₃ is hydrogen and R₄ is F, MeO— or CH₃C(O)O—, or those where R₅ is alkyl or aralkyl. Additional examples of compounds of formula I include those where R₃ and R₄ are F, or those where R₅ is t-butyl or benzyl.

In another aspect, the compounds of the invention include (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)azaalkylphosphonate analogues. Such compounds are represented by formula II:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₅ in which R₅ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ is hydrogen, alkyl, aryl, or aralkyl;

R₄ is hydrogen, alkyl, aryl, aralkyl, or —CO₂R₆ in which R₆ is hydrogen, alkyl, aryl, or aralkyl; and

n is 1 to 6;

or a pharmaceutically acceptable acid addition salt thereof.

Examples of compounds of formula II include those where R₁ is hydrogen, or those where R₂ is —CH₂OH, or —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁, or those where R₃ is hydrogen, or those where R₄ is alkyl or hydrogen. Additional examples of compounds of formula II include those where R₄ is ethyl.

In still another aspect, the compounds of the invention include (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)ethylphosphonate analogues. Such compounds are represented by formula III:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₈ in which R₈ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ is hydrogen and R₄ is hydroxy, halo, alkoxy or alkylcarbonyloxy; or

R₃ and R₄ can be taken together to form ═O;

R₅ and R₆ are hydrogen; or

R₅ and R₆ are halo; and

R₇ is hydrogen, alkyl, aryl, aralkyl, or —CO₂R₈ in which R₈ is hydrogen, alkyl, aryl, or aralkyl;

or a pharmaceutically acceptable acid addition salt thereof.

Examples of compounds of formula III include those where R₁ is hydrogen, or those where R₂ is —CH₂OH, or —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁, or those where R₃ and R₄ taken together form ═O; or those where R₅ and R₆ are F, or those where R₇ is alkyl. Additional examples of compounds of formula III include those where R₄ is OH or CH₃C(O)O—, those where R₇ is ethyl.

In yet another aspect, the compounds of the invention include pyridoxine malonate analogues such as, for example, ((2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethyl)malonates). Such compounds are represented by the formula IV:

in which

R₁ is hydrogen or alkyl;

R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₅ in which R₅ is hydrogen, alkyl, or aryl; or

R₂ is —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁;

R₃ and R₃′ are independently hydrogen or halo; or

R₃ and R₃′ taken together constitute a second covalent bond between the carbons to which they are substituent; and

R₄ is hydrogen or alkyl;

or a pharmaceutically acceptable acid addition salt thereof.

Examples of compounds of formula IV include those where R₁ is hydrogen, or those where R₂ is —CH₂OH, or —CH₂—O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁, or those where R₃ and R₃′ are independently hydrogen or F, or those where R₄ is hydrogen or ethyl. Additional examples of compounds of formula IV include those where R₃ and R₃′ taken together constitute a second covalent bond between the carbons to which they are substituent.

Pharmaceutically acceptable acid addition salts of the compounds of formulas I, II, III or IV include salts derived from nontoxic inorganic acids such as hydrochloric, nitric, phosphoric, sulfuric, hydrobromic, hydriodic, hydrofluoric, phosphorus, and the like, as well as the salts derived from nontoxic organic acids, such as aliphatic mono- and dicarboxylic acids, phenyl-substituted alkanoic acids, hydroxy alkanoic acids, alkanedioic acids, aromatic acids, aliphatic and aromatic sulfonic acids, etc. Such salts thus include sulfate, pyrosulfate, bisulfate, sulfite, bisulfite, nitrate, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide, iodide, acetate, trifluoroacetate, propionate, caprylate, isobutyrate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, mandelate, benzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, phthalate, benzenesulfonate, toluenesulfonate, phenylacetate, citrate, lactate, maleate, tartrate, methanesulfonate, and the like. Also contemplated are salts of amino acids such as arginate and the like and gluconate, galacturonate, n-methyl glutamine, etc. (see, e.g., Berge et al., J. Pharmaceutical Science, 66: 1-19 (1977)).

The acid addition salts of the basic compounds are prepared by contacting the free base form with a sufficient amount of the desired acid to produce the salt in the conventional manner. The free base form can be regenerated by contacting the salt form with a base and isolating the free base in the conventional manner. The free base forms differ from their respective salt forms somewhat in certain physical properties such as solubility in polar solvents, but otherwise the salts are equivalent to their respective free base for purposes of the present invention.

Syntheses

To prepare a compound of formula I, 3,4-isopropylidenepyridoxine-5-al is treated with a phosphonating agent, such as, a metal salt of di-tert-butyl phosphite or dibenzyl phosphite or diphenyl phosphite, to give protected alpha-hydroxyphosphonates. The protected alpha-hydroxyphosphonates can be treated with an acylating agent in an aprotic solvent, such as acetic anhydride in pyridine, or with an alkylating agent, such as methyl iodide and sodium hydride in tetrahydrofuran (THF), to give alpha-alkylcarbonyloxy or alpha-alkyloxyphosphonates esters respectively. Alternatively the protected alpha-hydroxyphosphonates can be treated with an agent to convert the hydroxyl group to a halogen, such as conversion to a fluoro group with DAST (diethylaminosulfurtrifluoride), to prepare the alpha-halophosphonate esters. The isopropylidene protecting group is removed from the fully protected alpha-substituted phosphonates by reacting them with water and an acid, such as 20% water in acetic acid, to prepare the pyridoxine-alpha-substituted phosphonate esters. The ester groups can be removed from the phosphonate groups of the pyridoxine-alpha-substituted phosphonate esters by further treating them with acid in water, such as 20% water in acetic acid, to give the corresponding phosphonic acids as can be seen in the following scheme.

Alternatively, to prepare a compound of formula I, 3,4-isopropylidenepyridoxine-5-halide is treated with a phosphonating agent, such as, a metal salt of di-tert-butyl phosphite or dibenzyl phosphite or diphenyl phosphite, to give protected phosphonates. The protected phosphonates are treated with a base, such as sodium hexamethyldisilazane (NaHMDS), and a halogenating agent, such as N-fluorobenzenesulfonimide (NFSi), to provide the dihalophosphonates as can be seen in the following scheme.

Alternatively, to prepare a compound of formula I, 3,4-isopropylidenepyridoxine-5-al is treated with an amine, such as p-methoxyaniline or p-aminobiphenyl, and a phosphonating agent, such as, a metal salt of di-tert-butyl phosphite, dibenzyl phosphite or diphenyl phosphite, to give protected aminophosphonates as can be seen in the following scheme.

To prepare a compound of formula II, 3,4-isopropylidenepyridoxine-5-amine is used as a starting material. The amine is treated with a haloalkylphosphonate diester, such as diethyl bromomethylphosphonate, to give 5′-phosphonoazaalkylpyridine diesters. Reaction of the 3,4-isopropylidene-5′-phosphonoazaalkylpyridoxine diesters with a trialkylsilyl halide, such as trimethylsilyl bromide, in an aprotic solvent, such as acetonitrile, removes the ester groups of the phosphonate diester to provide the corresponding free 3,4-isopropylidene-5′-phosphonoazaalkylpyridoxine diacid. The acetonide protecting group on the 3 and 4 position of the pyridoxine ring on the 3,4-isopropylidene-5′-phosphonoazaalkylpyridoxine diacid can be removed by reaction with acid and water, such as 20% water in acetic acid as can be seen in the following scheme.

To prepare a compound of formula III, 3,4-isopropylidenepyridoxine-5-al is reacted with a metal salt of a methyl, or dihalomethyl, phosphonate diester to produce 5′-phosphonoalkylpyridoxine diesters. The 5′-hydroxyl group of this product is acylated by an acylating agent, such as acetic anhydride in pyridine, to provide the corresponding O-acyl derivatives respectively, or oxidized to the keto functional group by an oxidizing agent, such as manganese dioxide. The blocking group at the 3 and 4 positions and the phosphonate ester groups of the hydroxy, alkylcarbonyloxy and keto phosphonate diesters are hydrolysed by reaction with acid and water, such as 20% water in acetic acid, to provide the corresponding phosphonate diesters, without the blocking group at the 3 and 4 position. These reactions are illustrated in the following scheme.

To prepare a compound of formula IV, the 3,4-isopropylidenepyridoxine-5-halide is reacted with a metal salt of a malonate diester to give the malonate diester derivative. The malonate diester derivative is hydrolysed in aqueous acid, such as 20% water in acetic acid, to remove the blocking group at the 3 and 4 position of the pyridoxine ring. The ester groups of the malonate are hydrolysed with water and base, such as sodium hydroxide in water, followed by acidification to provide the corresponding free malonic acid products. These reactions are illustrated in the following scheme.

Alternatively, to prepare a compound of formula IV, 3,4-isopropylidenepyridoxine-5-al is reacted with a condensing agent, such as titanium tetrachloride, and a malonate diester, such as diethyl malonate, to provide a vinylene malonate diester. The vinylene malonate diester is reacted with a fluorinating agent, such as Selectfluor, to give a dihalomalonate derivative. These reactions are illustrated in the following scheme.

One skilled in the art would recognize variations in the sequence of steps and would recognize variations in the appropriate reaction conditions from the analogous reactions shown or otherwise known that can be appropriately used in the above-described processes to make the compounds of formula I, II, III or IV herein.

The products of the reactions described herein are isolated by conventional means such as extraction, distillation, chromatography, and the like.

Methods of Use

In accordance with the present invention, the analogues can be used in the treatment of cardiovascular and related diseases; and in the treatment of diabetes mellitus and related diseases.

Cardiovascular and related diseases include, for example, hypertension, hypertrophy, congestive heart failure, heart failure subsequent to myocardial infarction, arrhythmia, myocardial ischemia, myocardial infarction, ischemia reperfusion injury, and diseases that arise from thrombotic and prothrombotic states in which the coagulation cascade is activated.

Diabetes mellitus and related diseases include, for example, hyperinsulinemia, insulin resistance, obesity, diabetes-induced hypertension, and damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin, connective tissue, and immune system.

“Treatment” and “treating” as used herein include preventing, inhibiting, alleviating, and healing cardiovascular and related diseases; diabetes mellitus and related diseases; or symptoms thereof. Treatment can be carried out by administering a therapeutically effective amount of a compound of the invention. A “therapeutically effective amount” as used herein includes a prophylactic amount, for example, an amount effective for preventing or protecting against cardiovascular and related diseases; diabetes mellitus and related diseases; or symptoms thereof, and amounts effective for alleviating or healing cardiovascular and related diseases; or diabetes mellitus and related diseases; or symptoms thereof.

A physician or veterinarian of ordinary skill readily determines a subject who is exhibiting symptoms of any one or more of the diseases described above. Regardless of the route of administration selected, the compounds of the present invention of formula I, II, III or IV or a pharmaceutically acceptable acid addition salt thereof can be formulated into pharmaceutically acceptable unit dosage forms by conventional methods known to the pharmaceutical art. An effective but nontoxic quantity of the compound is employed in treatment. The compounds can be administered in enteral unit dosage forms, such as, for example, tablets, sustained-release tablets, enteric coated tablets, capsules, sustained-release capsules, enteric coated capsules, pills, powders, granules, solutions, and the like. They can also be administered parenterally, such as, for example, subcutaneously, intramuscularly, intradermally, intramammarally, intravenously, and other administrative methods known in the art.

Although it is possible for a compound of the invention to be administered alone in a unit dosage form, preferably the compound is administered in admixture as a pharmaceutical composition. A pharmaceutical composition comprises a pharmaceutically acceptable carrier and at least one compound of formula I, II, III or IV, or a pharmaceutically acceptable acid addition salt thereof. A pharmaceutically acceptable carrier includes, but is not limited to, physiological saline, ringers, phosphate-buffered saline, and other carriers known in the art. Pharmaceutical compositions can also include additives, for example, stabilizers, antioxidants, colorants, excipients, binders, thickeners, dispersing agents, readsorpotion enhancers, buffers, surfactants, preservatives, emulsifiers, isotonizing agents, and diluents. Pharmaceutically acceptable carriers and additives are chosen such that side effects from the pharmaceutical compound are minimized and the performance of the compound is not canceled or inhibited to such an extent that treatment is ineffective.

Methods of preparing pharmaceutical compositions containing a pharmaceutically acceptable carrier and at least one compound of formula I, II, III or IV or a pharmaceutically acceptable acid addition salt thereof are known to those of skill in the art. All methods can include the step of bringing the compound of the invention in association with the carrier and additives. The formulations generally are prepared by uniformly and intimately bringing the compound of the invention into association with a liquid carrier or a finely divided solid carrier or both, and then, if necessary, shaping the product into the desired unit dosage form.

The ordinarily skilled physician or veterinarian will readily determine and prescribe the therapeutically effective amount of the compound to treat the disease for which treatment is administered. In so proceeding, the physician or veterinarian could employ relatively low dosages at first, subsequently increasing the dose until a maximum response is obtained. Typically, the particular disease, the severity of the disease, the compound to be administered, the route of administration, and the characteristics of the mammal to be treated, for example, age, sex, and weight, are considered in determining the effective amount to administer. Administering a therapeutic amount of a compound of the invention for treating cardiovascular and related diseases; diabetes mellitus and related diseases; or symptoms thereof, is in a range of 0.1-100 mg/kg of a patient's body weight, more preferably in the range of 0.5-50 mg/kg of a patient's body weight, per daily dose. The compound can be administered for periods of short and long duration. Although some individual situations can warrant to the contrary, short-term administration, for example, 30 days or less, of doses larger than 25 mg/kg of a patient's body weight is preferred to long-term administration. When long-term administration, for example, months or years, is required, the suggested dose should not exceed 25 mg/kg of a patient's body weight.

A therapeutically effective amount of a compound for treating the above-identified diseases or symptoms thereof can be administered prior to, concurrently with, or after the onset of the disease or symptom.

The compound also can be administered to treat cardiovascular and related diseases, for example, hypertrophy, hypertension, congestive heart failure, heart failure subsequent to myocardial infarction, myocardial ischemia, ischemia reperfusion injury, arrhythmia, or myocardial infarction. Preferably, the cardiovascular disease treated is hypertrophy or congestive heart failure. Still preferably, the cardiovascular disease treated is arrhythmia. Also preferably, the cardiovascular disease treated is ischemia reperfusion injury.

The compound can also be administered to treat cardiovascular diseases and other diseases that arise from thrombotic and prothrombotic states in which the coagulation cascade is activated, such as, for example, deep vein thrombosis, disseminated intravascular coagulopathy, Kasabach-Merritt syndrome, pulmonary embolism, myocardial infarction, stroke, thromboembolic complications of surgery, and peripheral arterial occlusion. A compound of the invention may also be useful in the treatment of adult respiratory distress syndrome, septic shock, septicemia, or inflammatory responses, such as edema and acute or chronic atherosclerosis, because thrombin has been shown to activate a large number of cells outside of the coagulation process, such as, for example, neutrophils, fibroblasts, endothelial cells, and smooth muscle cells.

Moreover, the compound can be administered concurrently with compounds that are already known to be suitable for treating the above-identified diseases. For example, methods of the invention include concurrently administering at least one compound of formula I, II, III or IV a pharmaceutically acceptable acid addition salt thereof, or a mixture thereof with a therapeutic cardiovascular compound to treat hypertrophy, hypertension, congestive heart failure, heart failure subsequent to myocardial infarction, myocardial ischemia, ischemia reperfusion injury, arrhythmia, or myocardial infarction. Preferably the cardiovascular disease treated is hypertrophy or congestive heart failure. Still preferably, the cardiovascular disease treated is arrhythmia. Also preferably, the cardiovascular disease treated is ischemia reperfusion injury.

Therapeutic cardiovascular compounds that can be concurrently administered with at least one compound of the invention include an angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, a calcium channel blocker, an antithrombolytic agent, a β-adrenergic receptor antagonist, a vasodilator, a diuretic, an α-adrenergic receptor antagonist, an antioxidant, and a mixture thereof. A compound of the invention also can be concurrently administered with PPADS (pyridoxal phosphate-6-azophenyl-2′,4′-disulphonic acid), also a therapeutic cardiovascular compound, or with PPADS and another known therapeutic cardiovascular compound as already described.

Preferably a therapeutic cardiovascular compound, which is concurrently administered with at least one compound of formula I, II, III or IV, a pharmaceutically acceptable acid addition salt thereof, or a mixture thereof, is an angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, or a diuretic. Still preferably, the therapeutic cardiovascular compound is an α-adrenergic receptor antagonist. Also preferably, the therapeutic cardiovascular compound is a calcium channel blocker.

These therapeutic cardiovascular compounds are generally used to treat cardiovascular and related diseases as well as symptoms thereof. A skilled physician or veterinarian readily determines a subject who is exhibiting symptoms of any one or more of the diseases described above and makes the determination about which compound is generally suitable for treating specific cardiovascular conditions and symptoms.

For example, myocardial ischemia can be treated by the administration of, for example, angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, a calcium channel blocker, an antithrombolytic agent, a β-adrenergic receptor antagonist, a diuretic, an α-adrenergic receptor antagonist, or a mixture thereof. In some instances, congestive heart failure can be treated by the administration of, for example, angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, a calcium channel blocker, a vasodilator, a diuretic, or a mixture thereof.

Myocardial infarction can be treated by the administration of, for example, angiotensin converting enzyme inhibitor, a calcium channel blocker, an antithrombolytic agent, a β-adrenergic receptor antagonist, a diuretic, an α-adrenergic receptor antagonist, or a mixture thereof.

Hypertension can be treated by the administration of, for example, angiotensin converting enzyme inhibitor, a calcium channel blocker, a β-adrenergic receptor antagonist, a vasodilator, a diuretic, an α-adrenergic receptor antagonist, or a mixture thereof.

Moreover, arrhythmia can be treated by the administration of, for example, a calcium channel blocker, a β-adrenergic receptor antagonist, or a mixture thereof.

Antithrombolytic agents are used for reducing or removing blood clots from arteries.

Hypertrophy can be treated by the administration of, for example, an angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, a calcium channel blocker, or a mixture thereof.

Ischemia reperfusion injury can be treated by the administration of, for example, an angiotensin converting enzyme inhibitor, an angiotensin II receptor antagonist, a calcium channel blocker, or a mixture thereof.

Known angiotensin converting enzyme inhibitors include, for example, captopril, enalapril, lisinopril, benazapril, fosinopril, quinapril, ramipril, spirapril, imidapril, and moexipril.

Examples of known angiotensin II receptor antagonists include both angiotensin I receptor subtype antagonists and angiotensin II receptor subtype antagonists. Suitable antiotensin II receptor antagonists include losartan and valsartan.

Suitable calcium channel blockers include, for example, verapamil, diltiazem, nicardipine, nifedipine, amlodipine, felodipine, nimodipine, and bepridil.

Antithrombolytic agents known in the art include antiplatelet agents, aspirin, and heparin.

Examples of known β-adrenergic receptor antagonists include atenolol, propranolol, timolol, and metoprolol.

Suitable vasodilators include, for example, hydralazine, nitroglycerin, and isosorbide dinitrate.

Suitable diuretics include, for example, furosemide, diuril, amiloride, and hydrodiuril.

Suitable α-adrenergic receptor antagonists include, for example, prazosin, doxazocin, and labetalol.

Suitable antioxidants include vitamin E, vitamin C, and isoflavones.

At least one compound of formula I, II, III or IV, a pharmaceutically acceptable acid addition salt thereof, or a mixture thereof and a therapeutic cardiovascular compound can be administered concurrently. “Concurrent administration” and “concurrently administering” as used herein includes administering a compound of the invention and a therapeutic cardiovascular compound in admixture, such as, for example, in a pharmaceutical composition or in solution, or as separate compounds, such as, for example, separate pharmaceutical compositions or solutions administered consecutively, simultaneously, or at different times but not so distant in time such that the compound of the invention and the therapeutic cardiovascular compound cannot interact and a lower dosage amount of the active ingredient cannot be administered.

At least one compound of formula I, II, III or IV, a pharmaceutically acceptable acid addition salt thereof, or a mixture thereof also can be administered to treat diabetes mellitus and related diseases. Preferably the disease treated is type I diabetes, type II diabetes, or obesity. Also preferably, the disease treated is damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin, connective tissue, or immune system. Still preferably, the disease treated is insulin resistance or hyperinsulinemia. And preferably, the disease treated is diabetes-induced hypertension.

The method of the invention also includes concurrently administering at least one compound of formula I, II, III or IV, a pharmaceutically acceptable acid addition salt thereof, or a mixture thereof with insulin and/or a hypoglycemic compound to treat diabetes mellitus and related diseases. The compound can be administered concurrently with insulin and/or a hypoglycemic compound to treat type I diabetes, type II diabetes, or obesity. Preferably the compound can be administered concurrently with insulin and/or hypoglycemic compound to treat damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin, connective tissue, or immune system. Still preferably, the compound can be administered concurrently with insulin and/or hypoglycemic compound to treat insulin resistance or hyperinsulinemia. Also preferably, the compound can be administered concurrently with insulin and/or hypoglycemic compound to treat diabetes-induced hypertension.

A compound typically can be administered concurrently with insulin to treat type I diabetes, type II diabetes, and related conditions and symptoms. For type II diabetes, insulin resistance, hyperinsulinemia, diabetes-induced hypertension, obesity, or damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin, connective tissue, or immune system, a compound can be administered concurrently with a hypoglycemic compound instead of insulin. Alternatively, a compound can be administered concurrently with insulin and a hypoglycemic compound to treat type II diabetes, insulin resistance, hyperinsulinemia, diabetes-induced hypertension, obesity, or damage to blood vessels, eyes, kidneys, nerves, autonomic nervous system, skin, connective tissue, or immune system.

“Concurrent administration” and “concurrently administering” as used herein includes administering at least one compound of formula I, II, III or IV, a pharmaceutically acceptable acid addition salt thereof, or a mixture thereof and insulin and/or a hypoglycemic compound in admixture, such as, for example, in a pharmaceutical composition, or as separate compounds, such as, for example, separate pharmaceutical compositions administered consecutively, simultaneously, or at different times. Preferably, if the compound and insulin and/or hypoglycemic compound are administered separately, they are not administered so distant in time from each other that the compound and the insulin and/or hypoglycemic compound cannot interact and a lower dosage amount of insulin and/or hypoglycemic compound cannot be administered.

Suitable hypoglycemic compounds include, for example, metformnin, acarbose, acetohexamide, glimepiride, tolazamide, glipizide, glyburide, tolbutamide, chlorpropamide, and a mixture thereof. Preferably the hypoglycemic compound is tolbutamide.

This invention will be further characterized by the following examples. These examples are not meant to limit the scope of the invention, which has been fully set forth in the foregoing description. Variations within the scope of the invention will be apparent to those skilled in the art.

EXAMPLES

All reagents used in the following Examples can be purchased from Aldrich Chemical Company (Milwaukee, Wis. or Allentown, Pa.).

Example 1 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)hydroxymethylphosphonate

Di-tert-butyl phosphite (16.3 g, 84 mmol) was added to a solution of NaH (3.49 g, 60%, 87.2 mmol) in THF (60 mL) under nitrogen at 0° C. The temperature of the resulting solution was raised to room temperature and the solution stirred for 15 min, then cooled to 0° C. again. To this solution, (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (11.41 g, 55.05 mmol) in THF (30 mL) was slowly added then the temperature raised to room temperature again and stirring continued for 2 h. The reaction was quenched by adding saturated NaHCO₃ (40 ml), and diluted with diethyl ether (200 mL). The ether layer was separated, washed with saturated aqueous NaHCO₃ (40 ml, 5%), then saturated brine (3×20 mL). The ether layer was dried (MgSO₄), filtered and evaporated to give crude product as a colorless solid. This solid was washed with hexane to remove the oil (from the NaH) and unreacted phosphite. The solid was recrystallized from a mixture of diethyl ether:hexane:ethyl acetate (230 mL:70 mL:15 mL). The colorless crystal (17.9 g, 81%) were filtered and washed with hexane.

¹H NMR (CDCl₃): 1.42 (9H, d), 1.46 (9H, d), 1.51 (6H, d), 2.38 (3H, s), 4.70 (1H, d), 4.89-5.13 (2H, m), 8.11 (1H, s).

³¹P NMR (H-decoupled, CDCl₃): 13.43 (s).

This structure can be represented by formula V:

Example 2 Synthesis of Dibenzyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)hydroxymethylphosphonate

Dibenzyl phosphate (1.89 g, 9.62 mmol) was mixed with the (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (1.00 g, 4.81 mmol) and stirred at room temperature for an hour. To this thick syrup was added activated basic alumina (1 g). The reaction mixture was then stirred at 80° C. for one hour. The reaction mixture was diluted with dichloromethane (50 mL), and filtered through Celite to remove alumina. The dichloromethane solution was washed with saturated, aqueous NaHCO₃ (20 mL), then saturated brine (3×10 mL). The dichloromethane layer was dried (MgSO₄), filtered and evaporated to give crude product as a colorless solid. The crude product was purified by silica gel column chromatography, using ether:hexanes (1:2) as eluent to give 1.3 g (58%).

¹H NMR (CDCl₃): 1.30 (3H, s), 1.45 (3H, s), 2.30 (3H, s), 4.86-4.99 (7H, s), 7.18-8.07 (10H, s), 8.08 (1H, s).

This structure can be represented by formula VI:

Example 3 Synthesis of (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)hydroxymethyl phosphonic Acid

The product of Example 1 above, of formula V, (10 g, 24.9 mmol) was dissolved in acetic acid (80% in water, 100 ml) and heated at 60° C. for 1 d. Colorless precipitate was formed, however, the reaction was not complete. Another 50 ml of 80% acetic acid in water was added to the mixture and the mixture stirred at 60° C. for another day. The solid was filtered off, washed with cold water, then methanol and dried to give a colorless solid (4.78 g, 77%).

¹H NMR (D₂O): 2.47 (3H, s), 4.75-4.79 (2H, m), 5.15-5.19 (1H, d), 7.82 (1H, s).

³¹P NMR (H-decoupled D₂O): 14.87 (s).

This structure can be represented by formula VII:

Example 4 Synthesis of Dibenzyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)fluoromethylphosphonate

The protected alpha-hydroxy phosphonate from Example 2 above of structure VI (1.0 g, 2.49 mmol) was dissolved in dichloromethane (10 mL), and the solution cooled to −78° C. To this solution was added diethylaminosulfurtrifluoride (DAST) (0.8 g, 4.98 mmol). The reaction was stirred at −78° C. under nitrogen for 20 minutes then allowed to stand at room temperature overnight. The reaction mixture was diluted with dichloromethane (50 ml), and washed with saturated, aqueous NaHCO₃ (125 mL). The dichloromethane layer was dried (MgSO₄), filtered and evaporated to give crude fluorophosphonate as a yellow solid. The crude product was purified by silica gel column chromatography, using ethyl acetate:hexanes (2:1) as the eluent to give 600 mg (60%).

¹H NMR (CDCl₃): 1.42 (3H, s), 1.52 (3H, s), 2.40 (3H, s), 4.91-4.97 (6H, m), 5.46-5.61 (1H, dd), 7.23-7.34 (10H, m), 8.01 (1H, s).

³¹P NMR (H-decoupled, F-coupled, CDCl₃): 16.36-16.08 (d).

This structure can be represented by formula VIII:

Example 5 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)fluoromethylphosphonate

The protected alpha-hydroxy phosphonate from Example 1 of structure V (3 g, 7.55 mmol) was dissolved in dichloromethane (30 mL), and the solution cooled to −78° C. To this solution was added diethylaminosulfurtrifluoride (DAST) (1.22 g, 7.57 mmol). The reaction was stirred at −78° C. under nitrogen for 5 minutes, quenched by addition of saturated, aqueous NaHCO₃ (2 mL) then allowed to warm room temperature. The reaction mixture was diluted with dichloromethane (50 ml), and washed with saturated, aqueous NaHCO₃ (2×20 mL). The dichloromethane layer was dried (MgSO₄), filtered and evaporated to give crude fluorophosphonate. The crude product was purified by silica gel column chromatography, using ethyl acetate:hexanes (1:1) as the eluent to give 350 mg (12%).

¹H NMR (CDCl₃): 1.44 (9H, s), 1.46 (9H, s), 1.52 (3H, s), 1.56 (3H, s), 2.41 (3H, s), 4.98-5.14 (2H, m), 5.32-5.52 (1H, dd), 8.03 (1H, s).

³¹P NMR (H-decoupled, F-coupled, CDCl₃): 6.53, 7.24.

¹⁹F NMR (H-decoupled, CDCl₃): −202.6, −203.0

This structure can be represented by formula IX:

Example 6 Synthesis of di-t-butyl (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)fluoromethyl Phosphonate

The protected di-t-butyl alpha-fluoro phosphonate from Example 5 of structure IX (3.2 g 7.8 mmol) was dissolved in acetic acid (80% in water, 50 ml) and heated at 60° C. for 24 hours. The pale yellow solid was filtered off, washed with cold water and methanol, and then dried to give a creamy solid (2.21 g, 70%).

¹H NMR (CDCl₃): 1.41 (9H, s), 1.44 (9H, s), 1.49 (3H, s), 1.51 (3H, s), 2.42 (3H, s), 4.99-5.07 (2H, m), 5.33-5.51 (1H, d, d), 8.04 (1H, s).

³¹P NMR (H-decoupled, F-Coupled, CDCl₃): 7.10-7.80 (d).

¹⁹F NMR (H, P-Coupled, CDCl₃): −203.07 to −202.61 (dd).

This structure can be represented by formula X:

Example 7 Synthesis of (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)fluoromethyl Phosphonic Acid

The protected di-t-butyl alpha-fluoro phosphonate from Example 5 of structure IX (200 mg, 0.5 mmol) was dissolved in acetic acid (80% in water, 15 ml) and heated at 75° C. for 24 hours. The solvent was removed by evaporation on a rotary evaporator using toluene to codistill the water. The crude product (183 mg) was purified by column chromatography on silica using chloroform:methanol:water (65:35:2) as eluent to give 60 mg (55%).

¹H NMR (D₂O): 2.46 (3H, bs), 4.65-4.90 (2H, dd), 5.81-6.01 (1H, dd), 7.74 (1H, bs).

³¹P NMR (H-decoupled, F-Coupled, CDCl₃): 9.3 (d).

¹⁹F NMR (H, P-Coupled, CDCl₃): −197 to −196 (dd).

This structure can be represented by formula XI:

Example 8 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)acetoxymethylphosphonate

The product of Example 1 above, of formula V (1.0 g, 2.49 mmol) was dissolved in dichloromethane (20 mL), the solution cooled to −5° C., and pyridine (2 mL) added, followed by acetic anhydride (1 mL). The reaction temperature was slowly allowed to reach room temperature. After one hour, the reaction was quenched by adding dilute aqueous hydrochloric acid (10%, 75 mL), and then diluted with dichloromethane (25 mL). Afterm separation of the aqueous layer the methylene chloride layer washed with saturated NaHCO₃ (2×20 mL). The dichloromethane layer was dried (MgSO₄), filtered and evaporated to give crude alpha acetoxy phosphonate as a colorless solid. The crude product was purified by silica gel column chromatography, using ethyl acetate:hexanes (2:1) as the eluent to give the product in good yield.

¹H NMR (CDCl₃): 1.31 (9H, d), 1.36 (9H, d), 1.49 (6H, d), 2.1 (3H s), 2.38 (3H, s), 5.04 (2H, d), 5.72-5.76 (1H, d), 8.11 (1H, s).

³¹P NMR (H-decoupled, CDCl₃): 13.43 (s).

This structure can be represented by formula XII:

Example 9 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methoxymethylphosphonate

The product of Example 1 above, of formula V (300 mg, 0.75 mmol) was dissolved in 15 ml of THF and reaction vessel was purged with N₂ gas. Sodium hydride (21 mg, 0.9 mmol) was added, and the solution stirred for 5 minutes before cooling to 0° C. Methyl iodide (160 mg, 1.1 mmol) was then injected and reaction vessel was gradually allowed to reach room temperature. TLC (ethyl acetate) indicated that the reaction was complete in 3 hours. The soution was diluted with methylene chloride (250 mL), washed with dilute, aqueous HCL (10%, 100 mL), then saturated, aqueous NaHCO₃, dried (MgSO₄) and evaporated. The crude product was chromatographed on silica gel using ethyl acetate/hexanes (1:1) as the eluent to give 132 mg (32%).

¹H NMR (CDCl₃): 1.41 (18H, s), 1.51 (3H, s), 1.54 (3H, s), 2.40 (3H, s), 3.33 (3H, s), 4.20-4.26 (1H, d), 5.05 (2H, bs), 8.01 (1H, s).

³¹ P NMR (H-decoupled, CDCl₃): 10.88 (s).

This structure can be represented by formula XIII:

Example 10 Synthesis of (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)acetoxymethyl Phosphonic Acid

The product of Example 8 above, of formula XII, (50 mg, 0.11 mmol) was added to acetic acid (80% in water) and stirred for 24 hours at 60° C. The solvent was removed by evaporation on a rotary evaporator using toluene to codistill the water. The crude product was purified by chromatography on silica gel column using CH₂Cl₂/MeOH/H₂O (65:35:4) as eluent to give 22.8 mg (76%).

¹H NMR (D₂O): 2.23 (3H, s), 2.51 (3H, s), 4.6-5.1 (2H, m), 6.1 (1H, d), 7.85 (1H, s).

This structure can be represented by formula XIV:

Example 11 Synthesis of (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methoxymethyl Phosphonic Acid

The product of Example 9 above, of formula XIII (132 mg, 0.32 mmol) was dissolved in acetic acid (80% in water, 25 mL) and stirred at 60° C. for 24 hours. The solvent was removed by evaporation on a rotary evaporator using toluene to codistill the water. The crude product was purified by chromatography on silica gel column using CH₂Cl₂/MeOH/H₂O (65:35:4) as eluent to give the product in good yield.

¹H NMR (D₂O): 2.52 (3H, s), 3.32 (3H, s), 4.47-4.88 (2H, m), 7.87 (1H, s).

³¹P NMR (H-decoupled, D₂O): 13.31 (s)

This structure can be represented by formula XV:

Example 12 Synthesis of Dibenzyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)difluoromethylphosphonate

To a solution of dibenzyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methylphosphonate (115 mg, 0.253 mmol) in THF (10 mL) was added NaHMDS (1 M, 0.56 mL, 0.56 mmol). The reaction mixture was cooled to −78° C. After 15 minutes, NFSi (237 mg, 0.75 mmol) was added to the reaction mixture. The temperature of the reaction mixture was slowly warmed to −20° C. The solution was diluted with Et₂O, washed with saturated NaHCO₃, water and brine, dried (MgSO₄) and evaporated. The crude product was chromatographed on silica using ethyl acetate:hexanes (2:1) as eluent to give the dibenzyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)difluoromethylphosphonate in good yields.

¹H NMR (CDCl₃) 1.53 (s, 6H), 2.45 (d, 3H), 5.34 (d, 2H), 7.09-7.39 (m, 14H), 8.29 (s, 1H).

³¹P NMR (CDCl₃) −2.15 (t).

¹⁹F NMR (CDCl₃) −105.7 (d).

This structure can be represented by formula XVI:

Example 13 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)(4-biphenylamino)methylphosphonate

The (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (424 mg, 2.19 mmol) and 4-aminobiphenyl (360 mg, 2.12 mmol) was refluxed in benzene (20 mL) under nitrogen, using a Dean-Stark trap to remove water, for 15 hours. The crude reaction mixture was evaporated, dissolved in THF (20 mL) and added to a flask containing di-t-butyl phosphite (955 mg, 5.12 mmol) in THF (20 mL) and NaH (270 mg, 57% in oil, 6.41 mmol) and stirred at 0° C. for two hours. The solution was diluted with Et₂O, washed with saturated, aqueous NaHCO₃ (40 mL), brine (20 mL), dried (MgSO₄) and evaporated. The crude product was chromatographed on silica gel using hexane:diethyl ether (2:1) to give di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)(4-biphenylamino)methylphosphonate in modest yields.

¹H NMR (CDCl₃) 8.40 (1H, d,), 7.50-7.41 (2H, m), 7.40-7.30 (4H, m), 7.28-7.10 (1H, m), 6.54 (1H, d), 5.24 (1H, dd,), 5.07 (1H, dd,), 4.65 (1H, dd,), 4.44 (1H, dd,) 2.40 (3H, d), 1.58 (3H, s), 1.49 (3H, s), 1.43 (9H, s), 1.41 (9H, s).

³¹P NMR (H-decoupled, CDCl₃): 13.1 (s).

This structure can be represented by formula XVII:

Example 14 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)(4-methoxyphenylamino)methylphosphonate

(α⁴,3-O-Isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (2.5 g, 12.1 mmol) and 4-aminoanisole (1.41 g, 11.4 mmol) was refluxed in benzene (100 mL) under nitrogen, using a Dean-Stark trap to remove water, for 15 hours. The reaction mixture was evaporated to give 3.02 g of crude imine. The crude imine (370 mg, 1.19 mmol) was dissolved in THF (20 mL) and added to a flask containing di-t-butyl phosphite (955 mg, 5.1 mmol) in THF (20 mL) and NaH (208 mg, 57% in oil, 4.94 mmol) and stirred at 0° C. for two hours and at room temperature for 24 hours. The solution was diluted with Et₂O, washed with saturated, aqueous NaHCO₃ (40 mL), brine (40 mL), dried (MgSO₄) and evaporated. The crude product was chromatographed on silica gel using hexane:diethyl ether (2:1) to give di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)(4-methoxyphenylamino)methylphosphonate in modest yields.

¹H NMR (CDCl₃) 8.09 (1H, d), 6.70-6.60 (2H, m), 6.47-6.36 (2H, m), 5.18 (1H, dd), 4.98 (1H, dd), 4.36-4.20 (2H, m), 3.65 (3H, s), 2.35 (3H, s), 1.54 (3H, s), 1.45 (3H, s), 1.39 (9H, s), 1.38 (9H, s).

³¹P NMR (decoupled, CDCl₃): δ 13.5 ppm.

This structure can be represented by formula XVIII:

Example 15 Synthesis of di-t-butyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-3-azabutylphosphonate

(α⁴,3-O-Isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methylbromide (Imperalli et al, J. Org. Chem., 60, 1891-1894 (1995)) (1.08 g. 4.0 mmol) in anhydrous DMF (20 ml) was treated with sodium azide (260 mg, 4.0 mmol) at room temperature. After one hour stirring at room temperature, the solution was extracted with diethyl ether (5×20 mL). The combined extracts were washed with water (10 mL), and brine (10 mL) and dried (MgSO₄). The solvent was evaporated and the crude product was purified by chromatography on silica gel using ethyl ether:hexanes (2:1) as eluent to give the azide as a colorless liquid (552mg, 60%).

¹H NMR (CDCl3, TMS) 1.57 (s, 6H), 2.42 (s, 3H), 4.23 (s, 2H), 4.86 (s, 2H), 7.96 (s, 1H). The purified azide (100 mg, 0.4 mmol) was dissolved in 95% ethanol and hydrogenated at 1 atm in presence of Lindlar catalyst (50 mg) for one hour. The catalyst was removed by filtration (Celite), and the solvent removed to give the crude, amine. Purification by chromatography on silica gel using CH₂Cl₂:MeOH (5:1) as eluent gave the product (80 mg, 82%) 1HNMR (CD₂Cl₂) 1.53 (s, 6H), 2.34 (s, 3H), 3.72 (s, 2H), 4.91 (s, 2H), 5.31 (s, 2H), 7.93 (s, 1H).

The (α⁴,3-O-Isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methylamine, from above, (416 mg, 2 mmol) was heated in saturated, aqueous sodium bicarbonate solution (10 mL) to 95° C., followed by slow addition of diethyl 2-bromoethylphosphonate (0.09 mL, 0.5 mmol) and the reaction stirred at 95° C. overnight. The solution is evaporated using toluene to codistill the water. The crude product is triturated with ethyl acetate to dissolve the crude organic product. Chromatography on silica gel using methylene chloride:methanol:hexanes (5:1:5) gave 76 mg (41%).

¹Hnmr (CDCl₃, TMS) 1.27 (t, 6H), 1.51 (s, 6H), 1.91 (t, 2H), 2.35 (s, 3H), 2.85 (t, 2H), 3.62 (s, 2H), 4.03 (m, 4H), 4.91 (s, 2H), 7.88 (s, 1H).

³¹P NMR (H-decoupled, CDCl₃): 31.00 (s).

This structure can be represented by formula XIX:

Example 16 Synthesis of (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-3-azabutylphosphonic Acid

The product of Example 15, of formula XIX (280 mg, 0.75 mmol) was stirred in a mixture of acetonitile (6 mL) and trimethylsilylbromide (TMSBr) (574 mg, 3.75 mmol) overnight at room temperature. The solvent was evaporated and the crude product was purified by chromatography on silica gel using dichloromethane:methanol:water (65:35:6) giving 188 mg (91%).

¹H NMR (D₂O) 1.65 (s, 6H), 2.02 (m, 2H), 2.42 (s, 3H), 3.40 (m, 2H), 4.24 (s, 2H), 5.12 (s, 2H), 8.11 (s, 1H).

³¹P NMR (H-decoupled, D₂O): 18.90 (s).

This structure can be represented by formula XX:

Example 17 Synthesis of (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-3-azabutylphosphonic Acid

The product of Example 16, of formula XX (168 mg, 0.53 mmol) was dissolved in acetic acid (80% in water, 10 mL) and heated to 60° C. for 5 hours. The solvent was removed by evaporation using toluene to codistill the water. The crude product was purified by chromatography on C-18 reverse phase silica gel using methanol:water (4:1) as eluent to give 57 mg (39%).

¹H NMR (D₂O) 2.05 (m, 2H), 2.52 (s, 3H), 3.38 (m, 2H), 4.42 (s, 2H), 4.96 (s, 2H), 7.87(s, 1H).

³¹P NMR (H-decoupled, D₂O): 18.90 (s).

This structure can be represented by formula XXI:

Example 18 Synthesis of Diethyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-2-hydroxyethylphosphonate

To a solution of diethyl methyl phosphite (0.29 mL, 2 mmol) in THF (20 mL) was added BuLi (2.5 M in hexane, 0.88 mL, 2.2 mmol), followed by (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (414 mg, 2 mmol) and the reaction mixture stirred at −78° C. for two hours. The solution was evaporated, dissolved in dichloromethane (50 mL), washed with saturated, aqueous NaHCO₃, dried (MgSO₄), evaporated and purified by chromatography on silica gel using ethyl acetate:hexane (1:2) as eluent to give 625 mg (87%).

¹H NMR(CDCl₃, TMS) 1.33 (m, 6H), 1.54 (s, 6H), 2.20 (m, 2H), 2.38 (s, 3H), 4.12 (m, 4H), 4.94 (s, 2H), 4.94 (s, 2H), 5.04 (t, 1H), 8.02 (s, 1H).

³¹P NMR (H-decoupled, CDCl₃): 29.03 (s).

This structure can be represented by formula XXII:

Example 19 Synthesis of Diethyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-2acetoxyethylphosphonate

The product of Example 18, of structure XXII (300 mg, 0.84 mmol) was acetylated in pyridine (0.5 mL) and acetic anhydride (0.25 mL) at 0+ C. for 5 minutes followed by 3 hours at room temperature. The solvent was removed by evaporation using toluene to codistill the solvents and the crude product was dissolved in dichloromethane (10 mL). This was washed with dilute HCl (10%, 5 mL), then saturated, aqueous NaHCO₃, dried (MgSO₄) and evaporated. Chromatography on silica gel using ethyl acetate:hexane (1:1) gave 258 mg (71%).

¹H NMR(CDCl₃, TMS) 1.21 (m, 6H), 1.54 (s, 6H), 2.03 (s, 3H), 3.97 (m, 4H), 5.07 (dd, 2H), 5.83 (dd, 1H), 8.02 (s, 1H).

³¹P NMR (H-decoupled, CDCl₃): 25.01 (s).

This structure can be represented by formula XXIII:

Example 20 Synthesis of Diethyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-2-hydroxy-1,1-difluoroethylphosphonate

To a solution of lithiumdiisopropylamide (LDA) (2.0 M, 1 mL, 2 mmol) in THF (5 mL) was added BuLi (0.5 M, 0.2 mL, 0.1 mmol). The mixture was cooled to −40° C. followed by the addition of diethyl difluoromethyl phosphonate (0.32 mL, 2 mmol) and the reaction mixture stirred at this temperature for 30 minutes. The solution was cooled to −78° C. and (α⁴,3-O-Isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (414 mg, 2 mmol) added in THF (2 mL). The solution was allowed to come to room temperature and stirred overnight. The solvent was evaporated, the residue dissolved in dichloromethane (20 mL), washed with saturated, aqueous NaHCO₃, dried (MgSO₄), and evaporated. Purification by chromatography on silica gel using ethyl acetate:hexane (2:1) gave 528 mg (67%)

¹H NMR (CDCl₃, TMS) 1.35 (t, 3H), 1.38 (t, 3H), 1.52 (s, 3H), 1.55 (s, 3H), 2.39 (s, 3H), 4.29 (m, 4H), 4.96 (dd, 3H), 8.09 (s, 1H).

¹⁹F NMR (CDCl₃) −125.99 (ddd), −114.55 (ddd).

³¹P NMR (H-decoupled, CDCl₃): 7.22 (dd).

This structure can be represented by formula XXIV:

Example 21 Synthesis of Diethyl (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-2-oxo-1,1-difluoroethylphosphonate

The product of Example 20, of structure XXIV, (420 mg, 1.06 mmol) was dissolved in toluene (50 mL) and MnO₂ (651 mg, 636 mmol) added. The mixture was heated to 50° C. and stirred overnight. The solution was cooled, filtered (Celite) and the solvent evaporated to give the crude product. Purification by chromatography on silica gel ethyl acetate (1:2) gave 201 mg (48%).

¹H nmr (CDCl₃, TMS) 1.39 (q, 6H), 1.56 (d, 6H), 2.51 (s, 3H), 4.34 (m, 4H), 5.08 (s, 2H), 8.88 (s, 1H).

¹⁹F NMR (CDCl₃) −109.86 (d).

³¹P NMR (H-decoupled, CDCl₃): 3.96 (t).

This structure can be represented by formula XXV:

Example 22 Synthesis of Diethyl (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-2-hydroxy-1,1-difluoroethylphosphonate

The product of Example 20, of structure XXIV (489 mg, 1.26 mmol) was dissolved in acetic acid (80% in water, 20 mL) and heated at 80° C. for 6 hours. The solvent was removed by evaporation by codistilling with toluene to remove last traces of acetic acid. The crude product was purified by chromatography on silica gel using dichloromethane:methanol:hexane (5:1:5) as eluent to give 171 mg (38%).

¹H NMR (CD₃OD) 1.32 (t, 3H), 1.37 (t, 3H), 2.43 (s, 3H), 4.30 (m, 4H), 4.93 (dd, 2H), 5.39 (m, 2H), 8.07 (s, 1H).

19F NMR (CD₃OD) −125.55 (dd), −115.77 (dd).

³¹P NMR (H-decoupled, MeOD): 7.82 (dd).

This structure can be represented by formula XXVI:

Example 23 Synthesis of Diethyl (3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)-2-oxo-1,1-difluoroethylphosphonate

The product of Example 21, of structure XXV (198 mg, 0.51 mmol) was dissolved in acetic acid (80% in water, 20 mL) and heated at 80° C. for 6 hours. The solvent was removed by evaporation by codistilling with toluene to remove last traces of acetic acid. The crude product was purified by chromatography on silica gel using dichloromethane:methanol:hexane (5:1:5) as eluent to give 25 mg (14%).

¹H NMR (CDCl₃, TMS) 1.38 (m, 6H), 2.37 (s, 3H), 4.33 (m, 4H), 4.92 (s, 1H), 7.88 (s, 1H).

¹⁹F (CDCl₃) −118.32 (d).

³¹P NMR (H-decoupled, CDCl₃): 5.90 (t).

This structure can be represented by formula XXVII:

Example 24 Synthesis of Diethyl (α⁴,3-O-isopropylidene-2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethyl)malonate

To a solution of diethyl malonate (0.76 mL, 798 mg, 4.98 mmol) in tetrahydrofuran (THF) (5 mL) was added LDA (5 M, 1 mL, 5.0 mmol) and stirred at 0° C. for 5 minutes. (α⁴,3-O-isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methylbromide (Imperalli et al, J. Org. Chem., 60, 1891-1894 (1995)) (1.36 g, 5.0 mmol) in THF (5 mL) was added. The reaction was stirred for 2 hours at 0° C. The solvent was evaporated and the residue was dissolved in Et₂O. This was washed with water, dried (MgSO₄) and evaporated to give the crude product. Purification of the crude mixture by chromatography on silica gel column using diethyl ether:hexane (1:1) gave the malonate derivative 769 mg (44%).

¹H NMR (CDCl₃, TMS) 1.23 (t, 6H), 1.54 (s, 6H), 2.37 (s, 3H), 3.04 (d, 2H), 3.63 (t, 1H), 4.18 (q, 4H), 4.86 (s, 2H), 7.87 (s, 1H).

This structure can be represented by formula XXVIII:

Example 25 Synthesis of Diethyl (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethyl)malonate

The product of Example 24, of structure XXVIII (769 mg, 2.18 mmol) was dissolved in acetic acid (80% in water, 25 mL) and heated at 80° C. for 3 hours. The solvent was removed by evaporation using toluene to codistill the solvents. The crude product was purified by chromatography on silica gel using ethyl acetate:hexane (4:1) as eluent to give 620 mg (91%).

¹H NMR (MeOD) δ 1.19 (t, 6H), 2.38 (s, 3H), 3.18 (d, J=7.6, 2H), 3.74 (t, J=7.7, 1H), 4.14 (q, 4H), 4.87 (s, 2H), 7.70 (s, 1H).

This structure can be represented by formula XXIX:

Example 26 Synthesis of (2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethyl)malonic Acid

The product of Example 25, of structure XXIX (620 mg, 2.0 mmol) was dissolved in aqueous NaOH (2 M, 4 mL) and stirred at room temperature for 1 hour. The reaction was quenched by adding 6 N HCl to give pH 4 to 5. The solution was diluted with 95% ethanol, separated from the precipitated salts and evaporated to give 540 mg.

¹H NMR (DMSO) 2.58 (s, 3H), 3.24 (d, 2H), 3.81 (t, 1H), 4.78 (s, 2H), 8.05 (s, 1H).

This structure can be represented by formula XXX:

Example 27 Synthesis of Diethyl (α⁴,3-O-Isopropylidene-2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridylmethylene)malonate

(α⁴,3-O-Isopropylidene-3-hydroxy-4-hydroxymethyl-2-methyl-5-pyridyl)methanal (Kortynk et al., J. Org. Chem., 29, 574-579 (1964)) (1.035 g, 5.5 mmol) was dissolved in benzene (10 mL) and, diethyl malonate (0.8 mL, 5 mmol), piperidine (0.08 mL) and acetic acid (0.09 mL) added. The solution was heated at 80° C. for 4 hours. The solution was diluted with diethyl ether (50 mL) and washed with dilute HCl, aqueous, saturated NaHCO₃, dried (MgSO₄) and evaporated to dryness. The crude product was purified by chromatography on silica gel using diethyl ether:hexane (1:2) as eluent to give 1.4 g (80%).

¹H NMR (CDCl₃) 1.24 (t, 3H), 1.33 (t, 3H), 1.55 (s, 6H), 2.42 (s, 3H), 4.27 (q, 2H), 4.31 (q, 2H), 4.83 (s, 2H), 7.52 (s, 1H), 8.06 (s, 1H).

This structure can be represented by formula XXXI:

Example 28 Synthesis of Diethyl 2-(α⁴,3-O-Isopropylidene-2-methyl-3-hydroxy-4-hydroxymethyl-5-pyridyl)-1,2-difluoro-1,1-dicarbethoxyethane

The product of Example 27, of structure XXXI ((354 mg, 1 mmol) was dissolved in acetonitrile (10 mL) and Pyr/HF (1 mL) added, followed by 1-(choromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate (Selectfluor reagent) (359 mg, 1 mmol). The reaction mixture was stirred at room temperature for 4 hours. The solution was diluted with diethyl ether (60 mL) and washed with water, NaHCO₃, and brine, dried (MgSO₄) and evaporated. Purification by chromatography on silica gel using diethyl ether:hexane (2:1) as eluent gave 90 mg (29%).

¹H NMR (CDCl₃, TMS) 1.21 (t, 3H), 1.26 (t, 3H), 2.48 (s, 3H), 3.7(d, 1H), 4.14-4.21(m, 4H), 5.01-5.03 (m, 2H), 5.03(d, 1H), 7.85 (s, 1H).

¹⁹F NMR (CDCl₃) −181.33, −181.44.

This structure can be represented by formula XXXII:

Although embodiments of the invention have been described above, it is not limited thereto, and it will be apparent to persons skilled in the art that numerous modifications and variations form part of the present invention insofar as they do not depart from the spirit, nature, and scope of the claimed and described invention.

All publications, patents, and patent documents described herein are incorporated by reference as if fully set forth. 

I claim:
 1. A compound of the formula IV

in which R₁ is hydrogen or alkyl; R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₅ in which R₅ is hydrogen, alkyl, or aryl; or R₂ is —CH₂O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁; R₃ and R₃′ are independently hydrogen or halo; or R₃ and R₃′ taken together constitute a second covalent bond between the carbons to which they are substituent; and R₄ is hydrogen; or a pharmaceutically acceptable acid addition salt thereof.
 2. A compound of claim 1, wherein R₁ is hydrogen.
 3. A compound of claim 1, wherein R₂ is —CH₂OH or —CH₂O-alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁.
 4. A compound of claim 1, wherein R₃ and R₃′ are independently hydrogen or F.
 5. A compound of claim 1, wherein R₃ and R₃′ taken together constitute a second covalent bond between the carbons to which they are substituent.
 6. A compound according to claim 1 having the formula


7. A pharmaceutical composition comprising a pharmaceutically acceptable carrier and a therapeutically effective amount of a compound of formula IV

in which R₁ is hydrogen or alkyl; R₂ is —CHO, —CH₂OH, —CH₃ or —CO₂R₅ in which R₅ is hydrogen, alkyl, or aryl; or R₂ is —CH₂.O- alkyl- in which alkyl is covalently bonded to the oxygen at the 3-position instead of R₁; R₃ and R₃′ are independently hydrogen or halo; or R₃ and R₃′ taken together constitute a second covalent bond between the carbons to which they are substituent; and R₄ is hydrogen or alkyl; or a pharmaceutically acceptable acid addition salt thereof.
 8. A pharmaceutical composition of claim 7, wherein the pharmaceutical composition is in a form suitable for enteral or parenteral administration. 